In modern communication implementations, high speed digital video systems approach a data rate of several gigabits per second (Gbps) for interface technologies such as HDMI (High Definition Multimedia Interface), DisplayPort, FireWire IEEE 1394, USB3.0 (Universal Serial Bus 3.0), etc. Due to the reduced component size and the resultant decreased span ESD (electrostatic discharge) jumps, system level ESD protection must be added on the board to pass ESD requirements set forth by the International Electomechanical Commission (IEC) in IEC 61000-4-2. Level 4 (±15 kV air, ±8 kV contact).
The on-board ESD protection component inevitably introduces some parasitic, particularly for a typically big capacitance of around 2.0 pF. This leads to a big variation of the channel impedance locally away from a nominal differential channel impedance (for example, of 100 ohms). As a result, such a high speed digital video system violates the required compliance specifications at the desired data rate due to degradation of the signal edge rate and an increase in the jitter.